CN115506758A

CN115506758A - Compact reservoir drainage pressure determination method, device, equipment and storage medium

Info

Publication number: CN115506758A
Application number: CN202110624879.7A
Authority: CN
Inventors: 陈福利; 闫林; 王少军; 王志平; 童敏; 袁大伟; 高建; 张祖波; 郭彬程; 白喜俊
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2021-06-04
Filing date: 2021-06-04
Publication date: 2022-12-23
Anticipated expiration: 2041-06-04
Also published as: CN115506758B

Abstract

Provided herein are tight reservoir drainage pressure determination methods, apparatus, devices, and storage media, wherein the methods comprise: acquiring mercury intrusion data of the core sample, wherein the mercury intrusion data comprise a plurality of mercury intrusion pressures and mercury intrusion saturation corresponding to each mercury intrusion pressure; calculating unit pressurization saturation increment corresponding to two adjacent mercury inlet pressures according to the mercury inlet pressure and the mercury inlet saturation; and selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the screening condition as a displacement pressure value. The method for determining the drainage pressure of the compact reservoir starts from the definition of the drainage pressure, determines the drainage pressure value according to the unit pressurization saturation increment, has more accurate result, and can provide reliable theoretical support for reservoir research and development; and the obtaining process is simple and convenient, and the efficiency of determining the displacement pressure of the compact reservoir is improved.

Description

Compact reservoir drainage pressure determination method, device, equipment and storage medium

Technical Field

The invention relates to the technical field of oil exploration and development, in particular to a method, a device, equipment and a storage medium for determining drainage pressure of a tight reservoir.

Background

The expulsion pressure, also known as the threshold pressure or threshold pressure, is the capillary pressure at which the non-wetting phase begins to continue into the maximum throat of the rock sample. The drainage pressure is an important index for researching the reservoir performance and the seepage performance of the reservoir, and the determination of the drainage pressure has important significance for reservoir evaluation.

The method for determining the expulsion pressure can be divided into four types, namely capillary pressure curve method, laboratory direct measurement method, geophysical evaluation method and influence factor comprehensive analysis method. Among them, the capillary pressure curve tangent method is the most commonly used method and can quickly determine the displacement pressure: and (3) taking a tangent line along the first inflection point of the flat part of the capillary pressure curve in a semilogarithmic coordinate, wherein the pressure point at which the extension line of the tangent line is intersected with the ordinate axis is the displacement pressure.

However, in the rock core mercury intrusion data of the tight oil reservoir, the capillary pressure curve mostly has no obvious flat part at the beginning of mercury intrusion stage, the method for determining the displacement pressure by using the corresponding capillary pressure when the curve begins to be stable is difficult to apply, and the tangent line of the capillary pressure curve is difficult to accurately make. Therefore, the method of cutting the capillary pressure curve has a large limitation. When the inflection point is difficult to determine, the pressure of one pressure measuring point with the mercury saturation difference of two adjacent measuring points being more than or equal to 2 percent back can be used as the displacement pressure. However, the determined displacement pressure value obtained by the method is usually higher than the actual value and has larger error; in addition, the mercury intrusion has a hysteresis effect, so that the obtained data cannot accurately reflect the characteristics of the actual displacement pressure.

In view of the above, the present disclosure aims to provide a tight reservoir drainage pressure determining method, apparatus, device and storage medium, so as to solve the problem in the prior art that the drainage pressure of a tight reservoir is not accurately obtained.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present disclosure is to provide a tight reservoir drainage pressure determination method, device, apparatus, and storage medium, so as to solve the problem in the prior art that it is inconvenient and inaccurate to obtain drainage pressure.

In order to solve the technical problems, the specific technical scheme is as follows:

in one aspect, provided herein is a tight reservoir drainage pressure determination method, comprising:

acquiring mercury intrusion data of the core sample, wherein the mercury intrusion data comprise a plurality of mercury intrusion pressures and mercury intrusion saturation corresponding to each mercury intrusion pressure;

calculating unit pressurization saturation increment corresponding to two adjacent mercury inlet pressures according to the mercury inlet pressure and the mercury inlet saturation;

and selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the screening condition as a displacement pressure value.

Specifically, the mercury inlet pressure corresponding to the unit supercharging saturation increment meeting the screening condition is selected as a displacement pressure value, and the method further comprises the following steps:

acquiring parameter data of a core sample, wherein the parameter data comprises pore throat distribution characteristics and permeability of the core sample;

determining a displacement pressure range according to the parameter data;

and selecting the mercury feeding pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value.

Further, the mercury injection pressure corresponding to the unit supercharging saturation increment meeting the screening condition is selected as a displacement pressure value, and the method further comprises the following steps:

drawing a capillary pressure curve according to the mercury inlet pressure value and the mercury inlet saturation;

according to the form and the value range of the capillary pressure curve, dividing the capillary pressure curve into a hemp skin effect division area and a throat initial mercury inlet area;

and selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value based on the divided hemp skin effect area and the throat initial mercury inlet area.

Further, the formula for calculating the unit supercharging saturation increment corresponding to two adjacent mercury inlet pressures is as follows:

SHg′|Pc＝△SHg/△Pc

wherein SHg' | Pc is unit pressurization saturation increment, Δ SHg is saturation increment, and Δ Pc is mercury inlet pressure increment.

Further, based on the partitioned pith-skin effect area and the throat initial mercury inlet area, selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value:

and selecting the mercury inlet pressure which meets the displacement pressure range and has unit pressurization saturation increment larger than or equal to 1%/MPa as a displacement pressure value based on the divided hemp skin effect area and the throat initial mercury inlet area.

Preferably, the method further comprises:

and correcting the displacement pressure value.

Preferably, the calculating, according to the mercury inlet pressure and the mercury inlet saturation, a unit pressurization saturation increment corresponding to two adjacent mercury inlet pressures further includes:

increasing the amount of mercury feed pressure and mercury feed saturation.

In another aspect, embodiments of the present specification further provide a tight reservoir drainage pressure determination apparatus, including:

the obtaining module is used for obtaining mercury intrusion data of the core sample, and the mercury intrusion data comprise a plurality of mercury intrusion pressures and mercury intrusion saturation corresponding to each mercury intrusion pressure;

the calculation module is used for calculating unit pressurization saturation increments corresponding to two adjacent mercury inlet pressures according to the mercury inlet pressure and the mercury inlet saturation;

and the selection module is used for selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the screening condition as a displacement pressure value.

On the other hand, embodiments of the present specification further provide a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the method steps provided in the foregoing technical solutions when executing the computer program.

On the other hand, the embodiments of the present specification further provide a computer readable storage medium, where a computer program is stored and executed, and when the computer program is executed by a processor, the computer program implements the method steps provided in the foregoing technical solutions.

By adopting the technical scheme, the method, the device, the equipment and the storage medium for determining the drainage pressure of the tight reservoir provided by the invention are based on the definition of the drainage pressure, the drainage pressure value of the tight reservoir is determined according to the unit pressurizing saturation increment, the result is more accurate, and reliable theoretical support can be provided for reservoir research and development; and the obtaining process is simple and convenient, and the efficiency of determining the displacement pressure of the tight reservoir is improved.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art, the drawings used in the embodiments or technical solutions in the prior art are briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 shows a schematic flow chart of a tight reservoir drainage pressure determination method provided in an embodiment herein;

FIG. 2 illustrates a flow diagram of a method of determining a displacement pressure;

fig. 3 (a) to 3 (c) show CT images of core samples;

fig. 4 (a) and 4 (b) show pore throat distribution characteristics of different core samples;

FIG. 5 shows a graph of permeability versus displacement pressure;

FIG. 6 shows a schematic representation of a capillary pressure curve for a core sample;

FIG. 7 shows a plot of unit boost saturation increase versus mercury inlet pressure;

fig. 8 shows a schematic structural diagram of a tight reservoir drainage pressure determination device provided by the embodiment;

fig. 9 shows a schematic structural diagram of a computer device provided in this embodiment.

Description of the symbols of the drawings:

10. an acquisition module;

20. a calculation module;

30. a selection module;

902. a computer device;

904. a processor;

906. a memory;

908. a drive mechanism;

910. an input/output module;

912. an input device;

914. an output device;

916. a presentation device;

918. a graphical user interface;

920. a network interface;

922. a communication link;

924. a communication bus.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of protection given herein.

It should be noted that the terms "first," "second," and the like in the description and claims herein and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments herein described are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.

Since Washburn proposed to measure the pore structure by using a non-wetting phase fluid in 1921, mercury intrusion instruments for measuring the pore structure characteristics of a porous medium by a mercury intrusion method are widely applied, and the advantages of rapidness, reliability, wide measurement range and the like are achieved, so that the industrial research and application of different industries are met. At present, the most advanced mercury intrusion instrument can realize full-automatic on-line test, the pressure measurement range is between 1psi and 60000psi, and the pressure resolution can be controlled within 1 psi; the diameter range of the measuring hole is 950 mu m to 3.6nm, and the measuring range is related to factors such as the characteristics of mercury, the characteristics of a sample and the pore structure and the like. The basic assumptions when measuring pore diameter by mercury intrusion are: (1) The pores are cylindrical and are described by using a capillary bundle theory; and (2) all the holes extend outward to the outer surface of the test specimen.

Displacement Pressure (abbreviated Pd or Pcd), also known as threshold Pressure or threshold Pressure, refers to the minimum Pressure required for the wetted phase fluid in a rock sample to begin Displacement by the non-wetted phase fluid. The drainage pressure has a direct relation with the pore throat, is an important index for researching the reservoir storage performance and seepage performance of the reservoir, and the determination of the drainage pressure has important significance for reservoir evaluation.

The method for determining the expulsion pressure can be roughly divided into four types, namely capillary pressure curve method, laboratory direct measurement method, geophysical evaluation method and influence factor comprehensive analysis method. Among them, the capillary pressure curve tangent method is the most commonly used method and can quickly determine the displacement pressure: and (3) taking a tangent line along the first inflection point of the flat part of the capillary pressure curve in a semilogarithmic coordinate, wherein the pressure point at which the extension line of the tangent line is intersected with the ordinate axis is the displacement pressure.

However, in the rock core mercury intrusion data of the tight oil reservoir, the capillary pressure curve mostly has no obvious flat part at the beginning of mercury intrusion stage, the method for determining the displacement pressure by using the corresponding capillary pressure when the curve begins to be stable is difficult to apply, and the tangent line of the capillary pressure curve is difficult to accurately make. Therefore, the method of cutting the capillary pressure curve has a large limitation. When the inflection point is difficult to determine, the pressure of one pressure measuring point with the mercury saturation difference of two adjacent measuring points being more than or equal to 3 percent back can be used as the displacement pressure. However, the determined displacement pressure value obtained by the method is usually higher than the actual value, and has larger error; and the obtained data can not accurately reflect the characteristics of the actual displacement pressure due to the hysteresis effect of the mercury vapor compression method.

In order to solve the above problems, embodiments herein provide a tight reservoir drainage pressure determining method, which can obtain drainage pressure more conveniently and reliably. Fig. 1 is a schematic diagram of the steps of a tight reservoir drainage pressure determination method provided in the examples herein, and the present specification provides the method operation steps as described in the examples or flow charts, but may include more or less operation steps based on conventional or non-inventive labor. The order of steps recited in the embodiments is merely one manner of performing the steps in a multitude of sequences, and does not represent a unique order of performance. When an actual system or apparatus product executes, it can execute sequentially or in parallel according to the method shown in the embodiment or the figures. Specifically, as shown in fig. 1, the method may include:

s110: acquiring mercury intrusion data of the core sample, wherein the mercury intrusion data comprise a plurality of mercury intrusion pressures and mercury intrusion saturation corresponding to each mercury intrusion pressure;

mercury is the one with the highest surface tension in common fluids, and this characteristic is often used in mercury intrusion tests to obtain the pore throat characteristics and displacement pressure of rock samples. During the mercury injection test, a plurality of test points are obtained, and the abscissa and the ordinate of each test point are respectively the mercury inlet saturation and the mercury inlet pressure, namely the mercury inlet pressure and the mercury inlet saturation are in one-to-one correspondence.

S120: calculating unit pressurization saturation increment corresponding to two adjacent mercury inlet pressures according to the mercury inlet pressure and the mercury inlet saturation; the mercury injection instrument can display the mercury injection pressure value corresponding to each test point, the calculation of the mercury injection saturation can adopt the conventional means in the field, for example, the gas detection permeability and the gas detection porosity of the rock sample can be respectively measured according to the natural gas industry standard after the pretreatment of the rock sample is finished and before the high-pressure mercury injection experiment is started, and the mercury injection saturation can be determined by means of the two parameters.

The corresponding mercury inlet pressure value and mercury inlet saturation for each test point collected in sample 1 are shown in table 1.

TABLE 1

As can be seen from table 1. The number of mercury intrusion data test points of the sample No. 1 is 30, wherein the number of the points with the mercury intrusion saturation of non-zero value is 29 (namely effective test points), and the number of the test points and the number of the effective test points are both sufficient. The mercury inlet pressure of each test point is arranged from large to small, the sectional mercury inlet saturation (%) is the difference of the mercury inlet saturation between two test points, and the unit pressurizing saturation increment corresponding to two adjacent test points is calculated according to the following formula:

SHg′|Pc＝△SHg/△Pc

wherein SHg' | Pc is the unit pressurization saturation increment, Δ SHg is the saturation increment, and Δ Pc is the mercury inlet pressure increment. The dimension of the unit supercharging saturation increment is%/MPa.

For example, the unit boost saturation increase for the 2 nd test point and the 3 rd test point is 29.910%/MPa, measured by

And (4) calculating.

S130: and screening the mercury inlet pressure value corresponding to the unit pressurization saturation increment meeting the screening condition as a displacement pressure value which can be recorded as Pcd0.

The embodiment of the specification provides a novel method for determining displacement pressure of a tight reservoir: the displacement pressure is determined according to the unit pressurization saturation increment between two adjacent test points, the conditions that the displacement pressure is high and the relation between the displacement pressure and the permeability is seriously contradicted caused by the existing displacement pressure determination method can be avoided, and the displacement pressure determination method for the tight reservoir provided by the embodiment of the specification can be suitable for determining the displacement pressure for treating the conventional mercury intrusion and the high-pressure mercury intrusion, and is wide in application range.

In some possible embodiments, as shown in fig. 2, step S130: the mercury pressure value that the unit pressure boost saturation increment that the screening satisfies the screening condition corresponds is regarded as arranging and is driven the pressure value, further does:

s210: acquiring parameter data of a core sample, wherein the parameter data comprises pore throat distribution characteristics and permeability;

pore throat is a generic term for pore space, which is the fundamental reservoir space in which fluids reside in the rock, and throat, which is an important channel for the seepage of fluids in the rock; the size and distribution of pore throats has a great influence on permeability, the larger the pore throats, the easier the fluid flows in the reservoir, and the displacement pressure is more directly related to the size of the pore throats.

Besides, the parameter data also comprises data obtained by observing a core CT image and a casting body slice, and data measured by constant-speed mercury injection and centrifugal nuclear magnetism.

As shown in fig. 3 (a) to 3 (c), the CT images of the core sample No. 1 are shown, fig. 3 (a) is a CT image of the core sample at a top view angle, fig. 3 (b) is a CT image of the core sample at a front view angle, and fig. 3 (c) is a three-dimensional image of the core sample, which can be used to explain pore throat characteristics of the sample.

As shown in fig. 4 (a) and 4 (b), the pore throat distribution characteristics of different core samples are shown, and in fig. 4 (a), the size distribution of the throat and the size distribution of the pores do not intersect, which indicates that the size of the pores is different from the size of the throat greatly; in FIG. 4 (b), the size distribution of the throat intersects with the size distribution of the pores, i.e., some of the pores are of a size comparable to the size of the throat. Therefore, in the mercury injection test, in the process that mercury enters pores with larger sizes at the initial stage of mercury injection and gradually occupies pores with smaller sizes, the mercury injection speed is gradually reduced along with the increase of pressure and even reduced to 0 (pore and throat switching area), and after the maximum throat breaks through, the mercury injection speed is rapidly increased along with the increase of mercury pressure. When the size of the pore is different from that of the throat, the change of the mercury inlet speed is more obvious; in summary, pore throat distribution characteristics are of guiding significance for mercury intrusion testing and determination of displacement pressure.

S220: determining a displacement pressure range according to the parameter data;

as shown in fig. 5, a typical graph of core sample permeability versus displacement pressure is shown. The permeability is restricted by the pore throat, the larger throat controls the permeability, the maximum throat corresponding to the displacement pressure occupies an important position, and the displacement pressure and the permeability have a better correlation under normal conditions. The relation curve of the permeability and the displacement pressure can be used as a reference basis for restraining and accurately determining the displacement pressure of the tight reservoir.

The porosity and permeability of sample No. 1 were measured as: 8.477% and 0.0848mD.

And obtaining the basic distribution characteristics of the displacement pressure of the compact reservoir core sample by adopting a quantitative description and statistical method according to the parameter data so as to determine the upper limit of the maximum throat distribution and provide basic constraint for accurately determining the displacement pressure. According to the parameter data, the displacement driving pressure of the No. 1 core sample can be calculated to be within the range of 0.5MPa to 2.94 MPa.

S230: and selecting the mercury feeding pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value.

Further, step 230: selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value, and further comprising the following steps:

s310: drawing a capillary pressure curve under a double logarithmic coordinate system according to the mercury inlet pressure value and the mercury inlet saturation; fig. 6 is a schematic diagram showing capillary pressure curves of core sample No. 1 in a log-log coordinate system.

S320: according to the form and the value range of the capillary pressure curve, a hemp skin effect division area and a throat initial mercury inlet area are divided from the capillary pressure curve, and a rapid mercury inlet area and a high-pressure deceleration mercury inlet area can also be divided.

During the mercury injection test, mercury forms some non-fit mercury vapor cavities on rough pit recesses, corners and ridges on the surface of a core sample, and the phenomenon is the 'pitted skin effect'. It should be noted that the pitted skin effect region mainly reflects the pore size characteristics of the core, and the pitted skin effect may not be seen in the absence of a core with developed pores. The more pronounced the lepping effect, the more developed the pores and the better the reservoir capacity.

As the pressure increases, the cavity gradually shrinks and eventually becomes filled with mercury and disappears. At this point, the mercury does not actually enter the pore-throat system. When a further increase in pressure begins to force mercury into the largest pore throat system, the pressure at which this occurs is called the displacement pressure, and the pith effect ends at the displacement pressure point. Therefore, the displacement pressure correction value can be determined according to the value range of the pith effect area and/or the value range of the initial mercury feeding shortage of the throat.

The rapid mercury inlet area mainly reflects the most developed part of the communicated throat, and is generally close to the median (non-normal distribution) or the average (normal distribution) of the radius of the throat; the high pressure slows down into the mercury zone and as the mercury inlet pressure increases, the throat becomes finer and decreases, thus, the mercury inlet rate decreases.

According to the mercury intrusion data in the table 1, the bast effect of the sample No. 1 is significant, the mercury inlet pressure corresponding to the bast effect region is in the range of 0.01369MPa to 0.4778MPa, and the main pore radius reflected by the bast effect is in the range of 1.5 μm to 53.7 μm; the initial mercury feeding area of the throat corresponds to the mercury feeding pressure in the range of 0.11MPa to 2.746 MPa. It should be noted that the hemp skin effect region and the initial mercury inlet region of the throat are partially overlapped, the initial mercury inlet region and the hemp skin effect region are a continuous pressure region, and at this time, in the initial region stage, there may be an overlapping region, and after the displacement pressure is finally determined, the region is clearly divided.

S330: and selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the displacement pressure range as a displacement pressure value according to the divided hemp skin effect area and the throat initial mercury inlet area.

Preferably, step S330 is further: and based on the divided regions, selecting the mercury feeding pressure which is within the range of displacement pressure and the increment of the unit pressurization saturation degree is more than or equal to 1%/MPa as the displacement pressure value.

Then, according to the mercury intrusion data in table 1, four test points (i.e., the test points 10 to 13) are located in the displacement pressure range (0.5 MPa to 2.94 MPa); and the mercury inlet pressure corresponding to the initial mercury inlet area of the throat is 0.11MPa to 2.746MPa; the unit pressurizing saturation increment of the test point 13 is 1.300%, and the requirement that the unit pressurizing saturation increment is larger than or equal to 1%/MPa is met, and because 1.300% is the unit pressurizing saturation increment between the test point 13 and the test point 12, the mercury feeding pressure corresponding to the test point 12 is determined to be the displacement pressure, namely the displacement pressure of the No. 1 sample is 2.048MPa.

It should be noted that, in the embodiment of the present specification, the selecting, as the displacement pressure value, the mercury inlet pressure at which the unit pressurization saturation increment is greater than or equal to 1%/MPa refers to a mercury inlet pressure value at a test point where the first mercury inlet pressure value breaks through 1%/MPa and is within a displacement pressure range and in accordance with a mercury inlet pressure interval of an initial mercury inlet area of the throat.

Preferably, in some embodiments, the method further comprises:

and correcting the displacement pressure value.

As can be seen from the medium-pressure mercury data in table 1, the difference between the mercury inlet pressure of the test point 14 and the mercury inlet pressure of the test point 13 is large, so that the difference between the unit pressurization saturation increment (5.357%/MPa) between the test point 13 and the test point 14 and the unit pressurization saturation increment (1.300%/MPa) between the test point 13 and the test point 12 is large, and therefore, the displacement pressure obtained according to the above steps is preferably corrected.

In some possible embodiments, new test point data (interpolation) may be added along the morphology and trend of the capillary pressure curve, e.g., (3.25mpa, 6.36%); the corrected displacement pressure value is still 2.048MPa, namely the displacement pressure value obtained by the method for determining the displacement pressure of the tight reservoir provided by the embodiment of the specification is high in accuracy.

Of course, the obtained displacement pressure value may also be corrected by some other method. For example, the tangent method: and (4) making a tangent according to a first inflection point in the capillary pressure curve, and obtaining a pressure value corresponding to an intersection point of a tangent extension line and a vertical coordinate as a displacement pressure correction value. The displacement pressure correction value may also be obtained by a 3% backset method (or a 2% backset method) of saturation increase. And correcting the displacement pressure value according to the displacement pressure correction value.

According to the mercury intrusion data in table 1, the displacement pressures obtained according to the existing 2% backset method or 3% backset method for saturation increase are both 2.746MPa (i.e. the mercury intrusion saturation corresponding to test point 14 is 7.364%, greater than 2% and 3%). However 7.364% is much greater than 2% or 3%; and when the pressure is 2.746MPa, the corresponding maximum pore throat radius is 0.267 μm, which is lower than the effective dense oil sweet spot standard and inconsistent with the sweet spot reflected by the porosity, therefore, the higher pressure of 2.746MPa is not suitable for being used as the displacement pressure value. That is to say, according to the tight reservoir displacement pressure determining method provided by the embodiments of the present specification, compared with the prior art, the accuracy of determining the displacement pressure value can be improved.

As shown in fig. 7, a relationship curve between the unit pressurizing saturation increment and the mercury inlet pressure may also be drawn according to the unit pressurizing saturation increment corresponding to the two adjacent test points calculated in step S120. The corresponding mercury inlet pressure indicated by the point PCd0 in the diagram is the displacement pressure. The curve can find and determine the pressure corresponding to the throat breakthrough, namely the displacement pressure, by utilizing the characteristic of rapid increase of the mercury saturation after the throat breakthrough.

To sum up, the method for determining displacement pressure of a tight reservoir provided in the embodiments of the present specification starts with the displacement pressure definition that "mercury intrusion breaks through the throat of the maximum communication pore and continuously enters the rock pore", and determines the displacement pressure according to the unit pressurizing saturation increment, by integrating the basic relationship between the pore throat distribution characteristic, the displacement pressure and the permeability, and the tight reservoir characteristics such as the pith effect and the initial mercury intrusion area of the throat, the result is more accurate, and reliable theoretical support can be provided for reservoir research and development; and the obtaining process is simple and convenient, and the efficiency of determining the displacement pressure of the tight reservoir is improved.

On the basis, the displacement pressure determined by the existing methods such as a saturation increment backspacing method and the like and a tangent method is also referred, and the displacement pressure value can be corrected and optimized.

As shown in table 2, the mercury intrusion data for core sample No. 2. And the basic data of the No. 2 core sample is measured to comprise the porosity of 10.17 percent and the permeability of 0.137mD.

TABLE 2

As can be seen from the mercury intrusion data in table 2, the total number of the pressure measurement points is 24, and the number of the mercury saturation non-0 points is only 11, which is the case of a small number of effective test points.

The displacement pressure range is preliminarily estimated to be between 0.5MPa and 2.0MPa according to parameter data such as porosity, permeability and the like. And observing the test point condition in the range interval, wherein only four test points are near the expected displacement pressure range. The speed of the saturation increasing along with the pressure increase is calculated, and a part of hemp skin effect characteristics show that the corresponding pore radius is reflected to correspond to the pressure of 0.523MPa, and the main pore radius is reflected to be more than 1.4 mu m.

Calculating the unit pressurizing saturation increment of two adjacent test points, and combining the value ranges of the pith effect area and the throat initial mercury inlet area and the displacement pressure range to obtain a displacement pressure value of 1.4928MPa (the unit pressurizing saturation increment between the test point 16 and the test point 17 is determined to be 6.311%/MPa, the unit pressurizing saturation increment between the test point 13 and the test point 14 is 2.318%/MPa and is also greater than 1%/MPa, but the test point is positioned in the pith effect area, so the mercury inlet pressure of the test point is not taken as the displacement pressure). Because pressure measurement points near the displacement pressure are sparse, and the unit supercharging saturation increment is large in mutation from 0.563%/MPa to 6.311%/MPa, the determined displacement pressure value may still have the problem of being inaccurate; the actual displacement pressure should be slightly higher than 1.4928MPa, and the displacement pressure is corrected by interpolation to finally determine the displacement pressure to be 1.613MPa.

When the distribution of the mercury intrusion data of the sample in the estimated displacement pressure range is not uniform enough, the arrangement of pressure measuring points can be considered again, the number of mercury intrusion pressure and mercury intrusion saturation is increased, and particularly, the measuring points near the displacement pressure are dense, so that the displacement pressure value can be accurately determined.

Table 3 shows mercury intrusion data for core sample No. 3, and it was determined that the base data for core sample No. 3 included porosity of 10.76% and permeability of 0.421mD.

TABLE 3

As can be seen from the mercury intrusion data in table 3, the total number of the test points is 14, and the displacement pressure range is preliminarily estimated to be between 0.25MPa and 0.735MPa through the parameter data such as porosity, permeability and the like, so that only three pressure measurement points are in the range, and the pressure measurement points are obviously few; the rate of increase of saturation with increasing pressure was calculated and no characteristic feature of the pockmarking effect was shown.

According to the embodiment of the specification, the mercury feeding pressure with the unit pressurization saturation increment of more than or equal to 1%/MPa is selected as the displacement pressure value, and the determined displacement pressure is 0.294MPa. In the table, a plurality of test points meet the displacement pressure range, the increment of the unit pressurizing saturation meets the condition that the increment is more than or equal to 1%/MPa (from the test point 1 to the test point 3), and the mercury feeding pressure value corresponding to the first test point (namely, the test point 1) meeting the condition is selected as the displacement pressure value.

However, the determined displacement pressure may have the problem of inaccuracy due to the fact that the mercury intrusion data pressure measuring point is thick and inaccurate. The displacement pressure determined by the existing saturation 3% backspacing method is 0.459Mpa, but the displacement pressure determined by the method is slightly higher because the mercury inlet saturation is increased from 2.577% to 9.74% and the span is far larger than 3%, and the displacement pressure enters a rapid mercury inlet area, which can be verified by a saturation pressure increment parameter.

According to throat radius distribution characteristics, logarithmic normal distribution is basically met, the drainage pressure (0.294 MPa) obtained according to the embodiment of the specification is corrected by an interpolation method, the corrected drainage pressure is 0.3679MPa, the corresponding maximum throat radius is 1.99 microns, and the drainage pressure is determined to be 0.3679MPa by integrating regional rules and experimental data.

Therefore, when the number of mercury intrusion data test points is insufficient, the accuracy of the displacement pressure determined by the mercury intrusion saturation difference backspacing method is affected if the mercury intrusion pressure difference and the saturation difference between two adjacent test points are large, and step S120: the calculating unit supercharging saturation increment corresponding to two adjacent mercury-in pressures according to the mercury-in pressure and the mercury-in saturation further comprises:

the number of mercury intrusion pressure values and mercury intrusion saturations (i.e., test points) are increased.

On the basis that the displacement pressure value is determined according to the unit supercharging saturation increment provided by the embodiment of the specification, the displacement pressure value is corrected by adopting an interpolation method or other methods, so that the method can be suitable for determining the displacement pressure of the compact reservoir under the condition that the number of test points and the number of effective test points are few, and the requirement for determining the displacement pressure under the condition that the number of effective test points is deficient is met.

In summary, the method for determining the drainage pressure of the compact reservoir provided in the embodiment of the present disclosure utilizes the definition of the drainage pressure, the distribution rule of pore throats, the characteristics of compact oil desserts, the permeability, the regional rule of the drainage pressure, and other parameters to determine the drainage pressure more accurately, and is applicable to determining the drainage pressure of various compact reservoirs, and more convenient and reliable.

As shown in fig. 8, embodiments of the present specification further provide a tight reservoir drainage pressure determination apparatus, including:

the obtaining module 10 is configured to obtain mercury intrusion data of the core sample, where the mercury intrusion data includes multiple mercury intrusion pressures and mercury intrusion saturations corresponding to the multiple mercury intrusion pressures;

the calculation module 20 is used for calculating unit pressurization saturation increments corresponding to all the mercury inlet pressure values according to the mercury inlet pressure and the mercury inlet saturation;

and the selection module 30 is used for selecting the mercury inlet pressure corresponding to the unit pressurization saturation increment meeting the screening condition as the displacement pressure value.

The advantages achieved by the device provided by the embodiment of the specification are consistent with those achieved by the method, and are not described in detail herein.

As shown in fig. 9, for a computer device provided for embodiments herein, the computer device 902 may include one or more processors 904, such as one or more Central Processing Units (CPUs), each of which may implement one or more hardware threads. The computer device 902 may also include any memory 906 for storing any kind of information, such as code, settings, data, etc. For example, and without limitation, the memory 906 may include any one or combination of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent fixed or removable components of computer device 902. In one case, when the processor 904 executes the associated instructions, which are stored in any memory or combination of memories, the computer device 902 can perform any of the operations of the associated instructions. The computer device 902 also includes one or more drive mechanisms 908, such as a hard disk drive mechanism, an optical disk drive mechanism, etc., for interacting with any memory.

Computer device 902 may also include an input/output module 910 (I/O) for receiving various inputs (via input device 912) and for providing various outputs (via output device 914). One particular output mechanism may include a presentation device 916 and an associated graphical user interface 918 (GUI). In other embodiments, the input/output module 910 (I/O), the input device 912, and the output device 914 may not be included, but merely as a computer device in a network. Computer device 902 may also include one or more network interfaces 920 for exchanging data with other devices via one or more communication links 922. One or more communication buses 924 couple the above-described components together.

Communication link 922 may be implemented in any manner, such as over a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. Communication link 922 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

Corresponding to the methods in fig. 1 to 2, the embodiments herein also provide a computer-readable storage medium having stored thereon a computer program, which, when executed by a processor, performs the steps of the above-described method.

Embodiments herein also provide computer readable instructions, wherein when executed by a processor, a program thereof causes the processor to perform the method as shown in fig. 1-2.

It should be understood that, in various embodiments herein, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments herein.

It should also be understood that, in the embodiments herein, the term "and/or" is only one kind of association relation describing an associated object, and means that there may be three kinds of relations. For example, a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter associated objects are in an "or" relationship.

Those of ordinary skill in the art will appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the components and steps of the various examples have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

It can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided herein, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electrical, mechanical or other form of connection.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the elements may be selected according to actual needs to achieve the objectives of the embodiments herein.

In addition, functional units in the embodiments herein may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present invention may be implemented in a form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The principles and embodiments of this document are explained herein using specific examples, which are presented only to aid in understanding the methods and their core concepts; meanwhile, for a person skilled in the art, according to the idea of the present disclosure, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present disclosure should not be construed as a limitation to the present disclosure.

Claims

1. A tight reservoir drainage pressure determination method is characterized by comprising the following steps:

2. The method according to claim 1, wherein the mercury inlet pressure corresponding to the unit pressurization saturation degree increment meeting the screening condition is selected as the displacement pressure value, and further the method comprises the following steps:

determining a displacement pressure range according to the parameter data;

3. The method according to claim 2, wherein the mercury inlet pressure corresponding to the unit pressurization saturation degree increment meeting the screening condition is selected as the displacement pressure value, and further the method comprises the following steps:

according to the form and the value range of the capillary pressure curve, dividing a pitted skin effect area and a throat initial mercury inlet area from the capillary pressure curve;

4. The method according to claim 3, wherein the formula for calculating the unit boost saturation increment corresponding to two adjacent mercury inlet pressures is as follows:

SHg′|Pc＝△SHg/△Pc

wherein SHg' | Pc is the unit pressurization saturation increment, Δ SHg is the saturation increment, and Δ Pc is the mercury inlet pressure increment.

5. The method according to claim 4, wherein the mercury inlet pressure corresponding to the unit pressurization saturation degree increment meeting the displacement pressure range is selected as a displacement pressure value based on the divided hemp-skin effect area and the throat initial mercury inlet area, and the displacement pressure value is as follows:

and selecting the corresponding mercury inlet pressure which is within the displacement pressure range and is greater than or equal to 1%/MPa of the unit pressurization saturation increment as a displacement pressure value based on the divided hemp skin effect area and the throat initial mercury inlet area.

6. The method of claim 1, further comprising:

and correcting the displacement pressure value.

7. The method according to claim 1, wherein calculating the unit pressurizing saturation increment corresponding to two adjacent mercury-in pressures according to the mercury-in pressure and the mercury-in saturation further comprises:

increasing the amount of mercury feed pressure and mercury feed saturation.

8. A tight reservoir drainage pressure determination apparatus, comprising:

9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method steps of any of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores an executable computer program which, when executed by a processor, carries out the method steps of any one of claims 1 to 7.